Intelligent electronic device and method thereof

ABSTRACT

An intelligent electronic device (IED) having a gain control unit adapted to selectively regulate operating ranges of output signals of a sensing circuit of the device is described. In one embodiment, the IED is a digital electric power and energy meter, which operating ranges for supply voltages and supply currents of electrical services may be adjusted to match pre-determined ranges for input signals of a data acquisition system or a data processing module of the meter.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/103,250, filed Dec. 11, 2013, now U.S. Pat. No. 9,194,898, which is acontinuation of U.S. patent application Ser. No. 13/315,521, filed Dec.9, 2011, now U.S. Pat. No. 8,620,608, which is a continuation of U.S.patent application Ser. No. 12/056,955, filed Mar. 27, 2008, now U.S.Pat. No. 8,078,418, which is a continuation-in-part application of U.S.patent application Ser. No. 12/036,356 filed on Feb. 25, 2008, now U.S.Pat. No. 7,899,630, which is a continuation application of U.S. patentapplication Ser. No. 11/341,802 filed on Jan. 27, 2006 entitled“METERING DEVICE WITH CONTROL FUNCTIONALITY AND METHOD THEREOF”, nowU.S. Pat. No. 7,337,081, which claims priority to expired U.S.Provisional Patent Application Ser. No. 60/647,669 filed on Jan. 27,2005, the contents of which are hereby incorporated by reference intheir entireties.

U.S. patent application Ser. No. 12/056,955 also claims priority toexpired U.S. Provisional Patent Application No. 60/920,198, filed onMar. 27, 2007, which is herein incorporated by reference.

FIELD OF THE INVENTION

The present disclosure relates generally to the field of intelligentelectronic devices for electrical utility services and, morespecifically, to digital electrical power and energy meters for theelectrical utility services.

BACKGROUND OF THE INVENTION

Electrical utilities gradually replace traditional means for managingand controlling the distribution and consumption of electrical power toindustrial and residential customers with intelligent electronic devices(“IEDs”), such as digital electric power and energy meters, ProgrammableLogic Controllers (“PLCs”), electronically-controlled Remote TerminalUnits (“RTUs”), protective relays, fault recorders, and the like. Inoperation, the IEDs provide a broad selection of monitoring and meteringfunctions and may be accessed via electronic or fiber-optic means ofcommunications.

While it is efficient to use a single model of a respective IED bydifferent groups of customers or in different electrical networks,exposure of the IED to multiple ranges of supply voltages and currentsmay have a detrimental effect on its operability and/or accuracy of themeasurements performed by the IED.

Therefore, further improvements in the intelligent electronic deviceswould be desirable.

SUMMARY

One aspect of the present disclosure provides a digital electrical powerand energy meter having a gain control unit adapted to selectivelyregulate operating ranges of output signals of a sensing circuit of themeter. In operation, the operating ranges corresponding to supplyvoltages and supply currents of different electrical services may beadjusted to match pre-determined ranges for input signals of a dataacquisition system or a data processing module of the meter. In oneembodiment, the adjustments are performed dynamically, during monitoringthe respective electrical service or load.

According to an aspect of the present disclosure, an intelligentelectronic device, e.g., a power or energy meter, is provided includinga metering module including: a sensing circuit adapted for monitoringsupply voltages or supply currents of an AC electrical service, thesensing circuit having voltage sensors and current sensors; a gaincontrol unit coupled to the sensing circuit and adapted for selectivelyadjusting amplitudes of output signals of the sensing circuit; and adata acquisition system coupled to the gain control unit; and aprocessing module adapted for processing data obtained using themetering module, wherein the gain control unit is adapted for matchingoperating ranges of the output signals of the sensing circuit with atleast one pre-determined range for input signals of the data acquisitionsystem. The gain control unit includes a plurality of gain-controlledamplifiers which gain factors are selectively controlled using feedbacksignals generated by the data acquisition system or the processingmodule, wherein the gain factors are selectively determined for outputsignals of the voltage sensors or output signals of the current sensors.At least a portion of the gain factors is selectively determined priorto measuring the supply voltages or the supply currents or determinedsubstantially simultaneously with measurements of the supply voltages orthe supply currents. The at least one pre-determined range includes apre-determined range for voltages and a pre-determined range forcurrents, wherein the pre-determined range for the voltages correspondsto the supply voltages of about 0 to 150V and the pre-determined rangefor the currents corresponds to the supply currents of about 0 to 2 A.

In another aspect of the present disclosure, the device is selected fromthe group consisting of a digital electrical power and energy meter, aProgrammable Logic Controller (PLC), a Remote Terminal Unit, aprotective relay, or a fault recorder.

In a further aspect, a method of measuring supply voltages and currentsof an AC electrical service using an intelligent electronic deviceincludes (a) monitoring the supply voltages or the supply currents usinga sensing circuit of the device; and (b) selectively adjusting operatingranges of at least a portion of output signals of the sensing circuit tomatch at least one pre-determined range for input signals of a dataacquisition system of the device, wherein the at least onepre-determined range includes a pre-determined range for voltages and apre-determined range for currents. A computer readable medium storing aprogram code that, when executed by a computer, facilitates execution ofthe method or portions thereof is also provided.

In a still further aspect of the present disclosure, an intelligentelectronic device is provided including a metering module adapted formeasuring or calculating at least one parameter of an AC electricalservice; and a processing module adapted for processing data obtainedusing the metering module; wherein the processing module is adapted forperforming calibrating measurements of the at least one parameter in aplurality of calibrating points, wherein the at least one parameter is asupply voltage or a supply current. The calibrating points include (i)69V, 120V, 220V, and 480V for the supply voltage and (ii) 250 mA, 500mA, 1 A, and 5 A for the supply current. The calibrating measurementsare performed using certified sources of the at least one parameter. Theresults of measuring or calculating the at least one parameter arelinearly interpolated using data of the calibrating measurements at thecalibrating points adjacent to a data point of the at least oneparameter. Furthermore, the processing module is further adapted forperforming the calibrating measurements of the at least one parameter ata plurality of calibrating frequencies, wherein results of measuring orcalculating the at least one parameter are linearly interpolated usingdata of the calibrating measurements performed at the calibratingfrequencies adjacent to an AC frequency of the AC electrical service.The plurality of the calibrating frequencies includes 50 Hz and 60 Hz.The device further includes a communication module adapted fortransmitting to a remote terminal results of the calibratingmeasurements or results of measuring or calculating the at least oneparameter.

In another aspect, a method of measuring at least one parameter of an ACelectrical service using an intelligent electronic device includesperforming calibrating measurements of the at least one parameter in aplurality of calibrating points using certified sources of the at leastone parameter; and linearly interpolating results of measuring the atleast one parameter using data of the calibrating measurements performedat the calibrating points adjacent to a data point of the at least oneparameter, wherein the at least one parameter is a supply voltage or asupply current. In other aspects, the method further includes performingthe calibrating measurements of the at least one parameter at aplurality of calibrating frequencies, and linearly interpolating resultsof measuring the at least one parameter using data of the calibratingmeasurements performed at the calibrating frequencies adjacent to an ACfrequency of the AC electrical service.

According to a further aspect of the present disclosure, an intelligentelectronic device is provided including a metering module adapted formeasuring or calculating at least one parameter of an AC electricalservice; and a processing module adapted for processing data obtainedusing the metering module; wherein the metering and processing modulesform (i) first measuring channels time-locked to zero-crossing points ofsupply voltages or supply currents of the AC electrical service, and(ii) second measuring channels time-locked to pre-determined moments oftime. The zero-crossing points are moments of time when a polarity ofthe supply voltages or the supply currents changes from a negativepolarity to a positive polarity or when a polarity of the supplyvoltages or the supply currents changes from a positive polarity to anegative polarity. The first measuring channels are adapted formeasuring or calculating the at least one parameter during apre-determined number of cycles of an AC frequency of the AC electricalservice and the second measuring channels are adapted for measuring orcalculating the at least one parameter during a pre-determined timeinterval.

In a further aspect, the first measuring channels are adapted formeasuring or calculating numerical values of the at least one parameterselected from the group consisting of a line voltage, a line current, aphase voltage, a phase current, or a root mean square (RMS) valuethereof; energy, revenue, real power, reactive power, total power, and apower factor and the second measuring channels are adapted for measuringor calculating the at least one parameter selected from the groupconsisting of a waveform of a line voltage, a waveform of a linecurrent, a waveform of a phase voltage, a waveform of a phase current;and a total harmonic distortion or harmonics thereof.

A method of measuring or calculating at least one parameter of an ACelectrical service using an intelligent electronic device is providedincluding (a) forming first measuring channels time-locked tozero-crossing points of supply voltages or supply currents of the ACelectrical service; and (b) forming second measuring channelstime-locked to pre-determined moments of time. The zero-crossing pointsare moments of time when a polarity of the supply voltages or the supplycurrents changes from a negative polarity to a positive polarity or whena polarity of the supply voltages or the supply currents changes from apositive polarity to a negative polarity. In one aspect, step (a)includes measuring or calculating the at least one parameter during apre-determined number of cycles of an AC frequency of the AC electricalservice, wherein the at least one parameter is selected from the groupconsisting of a line voltage, a line current, a phase voltage, a phasecurrent, or a root mean square (RMS) value thereof energy, revenue, realpower, reactive power, total power, and a power factor. In a differentaspect, the step (a) includes measuring or calculating the at least oneparameter during a pre-determined time interval, wherein the at leastone parameter is selected from the group consisting of a waveform of aline voltage, a waveform of a line current, a waveform of a phasevoltage, a waveform of a phase current; and a total harmonic distortionor harmonics thereof. A computer readable medium storing a program codethat, when executed by a computer, facilitates execution of the methodof or portions thereof is also provided.

In a still further aspect, an intelligent electronic device includes ametering module adapted for measuring or calculating at least oneparameter of an AC electrical service; a processing module adapted foradministering operation of the device and processing data obtained usingthe metering module; and a user interface unit adapted for displayingresults of measuring or calculating the at least one parameter orconfiguration settings of the device, wherein (i) the user interfaceunit is coupled to the processing module using a serial data interfaceand (ii) the user interface unit comprises a decoder of instructionsreceived via the serial data interface and a display adapted fordisplaying alphanumeric information contained in said instructions. Inone aspect, the alphanumeric information comprises a pre-determinedportion of the results of measuring or calculating the at least oneparameter and portions of the configuration settings of the device. Theuser interface unit further includes a plurality of indicatorsselectively adapted to identify portions of the configuration settingsof the device. In another aspect, the at least one parameter is selectedfrom the group consisting of a line voltage, a line current, a phasevoltage, a phase current, and a total harmonic distortion (THD) or aroot mean square (RMS) value thereof; energy, revenue, real power,reactive power, total power, and a power factor.

In a further aspect, each of the fields comprises a plurality ofsegments, each segment adapted for displaying numerals from 0 to 9, atleast some letters or portions thereof, and a decimal point. Thesegments may include liquid crystal display (LCD) segments or lightemitting diode (LED) segments. The user interface unit further includesa plurality of indicators adapted to identify a numerical or relativevalue of the at least one parameter, wherein the indicators includelight emitting diode (LED) indicators. The serial data interfaceincludes a RS-485 interface or Serial Peripheral Interface (SPI).

According to yet another aspect of the present disclosure, anintelligent electronic device, is provided including a metering moduleadapted for measuring or calculating at least one parameter of an ACelectrical service, the metering module disposed on a first printedcircuit board (PCB); a processing module adapted for administeringoperation of the device and processing data obtained using the meteringmodule; a communication module adapted for coupling to a remoteterminal; and a user interface unit adapted for displaying apre-determined portion of results of measuring or calculating the atleast one parameter or configuration settings of the device, wherein (i)a first portion of the communication module is disposed on a second PCB,and (ii) the processing module, the user interface unit, and a secondportion of the communication module are disposed on a third PCB having afirst surface and a second surface opposing the first surface. The userinterface unit is disposed on the first surface of the third PCB and theprocessing module is disposed on the second surface of the third PCB.The first portion of the communication module comprises an infra-red(IR) communication device, wherein a transmitter/receiver of the IRcommunication device is disposed on the first surface of the third PCBand the second portion of the communication module comprises a networkcommunication card coupled to the processing module via a connectordisposed in the second surface of the third PCB. The networkcommunication card supports at least one of a RS-485 communicationprotocol, Modbus protocol or a DNP 3.0 communication protocol andprovides a KYZ energy pulse output.

In another aspect of the present disclosure, the second portion of thecommunication module further includes at least one input/output (I/O)card coupled to the processing module via a connector disposed in thesecond surface of the third PCB. The at least one I/O card isselectively adapted for supporting bi-directional data exchanges usinganalog 0-1 mA signals, analog 4-20 mA current loop signals, digitalsignals, relay contacts, solid-state contacts, fiber-optic signals, a10/100BaseT Ethernet communication protocol, or a Modbus/TCPcommunication protocol.

The user interface unit comprises a display, a plurality of indicators,and a plurality of user controls, wherein the display comprises aplurality of fields, each field adapted for selectively displaying anumerical value of the at least one parameter or an alpha-numericconfiguration setting of the device. Each of the fields comprises aplurality of segments, each segment adapted for displaying numerals from0 to 9, at least some letters or portions thereof, and a decimal point.Each of the fields includes four said segments. The segments are liquidcrystal display (LCD) segments or light emitting diode (LED) segments.The indicators are adapted for selectively identifying the at least oneparameter, wherein a portion of indicators is arranged to indicate anumerical or relative value of the at least one parameter. The usercontrols includes multi-functional pushbuttons selectively adapted foractivating functions of the device or entering user commands.

An intelligent electronic device is provided which includes a meteringmodule adapted for measuring or calculating at least one parameter of anAC electrical service; and a processing module adapted for administeringoperation of the device and processing data obtained using the meteringmodule, wherein the processing module is adapted for (i) configuringpre-determined settings for the at least one parameter and (ii)detecting events when a numerical value of the at least one parameterbecomes equal to or exceeds the pre-determined settings, wherein thepre-determined settings comprise minimal acceptable values or maximumacceptable values of the at least one parameter. The at least oneparameter is selected from the group consisting of a line voltage, aline current, a phase voltage, a phase current, and a total harmonicdistortion (THD) or a root mean square (RMS) value thereof; energy,revenue, real power, reactive power, total power, and a power factor.The device further includes a communication module adapted fortransmitting to a remote terminal records relating to the pre-determinedsettings and timing of the detected events, wherein the communicationmodule is adapted for transmitting the records using at least one ofRS-485, DNP 3.0, 10/100BaseT Ethernet, or Modbus/TCP communicationprotocols. The communication module is further adapted for reporting thedetected events in forms of a change of: a state of at least one relaycontact or solid-state contact, a digital state of at least one outputterminal, or a numerical value of an analog signal.

In a further aspect of the present disclosure, a method of monitoring aparameter of an AC electrical service is provided including configuringat least one pre-determined setting for the parameter; and detectingevents when a numerical value of the parameter becomes equal to orexceeds the at least one pre-determined setting, wherein the at leastone pre-determined setting is a minimal acceptable value or a maximumacceptable value of the parameter. The at least one parameter isselected from the group consisting of a line voltage, a line current, aphase voltage, a phase current, and a total harmonic distortion (THD) ora root mean square (RMS) value thereof; energy, revenue, real power,reactive power, total power, and a power factor.

In another aspect, the method further includes transmitting recordsrelating to the at least one pre-determined setting and timing of thedetected events using a series communication protocol. In anotheraspect, the method further includes reporting the detected events informs of a change of: a state of at least one relay contact orsolid-state contact, a digital state of at least one output terminal, ora numerical value of an analog signal.

In still a further aspect of the present disclosure, an intelligentelectronic device is provided including a metering module adapted formeasuring or calculating at least one parameter of an AC electricalservice; a processing module adapted for administering operation of thedevice and processing data obtained using the metering module; and acommunication module adapted for coupling to a remote terminal, wherein(i) the processing module is adapted for presenting a data point of theat least one parameter as a datagram having a plurality of datasegments, and (ii) the communication module is adapted for transmittingthe datagrams, wherein the datagram has a pre-determined number of thedata segments; and a content of each data segment of the datagram has apre-calculated numerical value. An average numerical value of contentsof the data segments of the datagram is a pre-determined numericalvalue. The pre-determined numerical value is equal to an instantaneousnumerical value of the at least one parameter. The instantaneousnumerical value of the at least one parameter is a fractional numericalvalue defined with accuracy exceeding binary resolution of thecommunication module or the remote terminal. The at least one parameteris selected from the group consisting of a line voltage, a line current,a phase voltage, a phase current, and a total harmonic distortion (THD)or a root mean square (RMS) value thereof; energy, revenue, real power,reactive power, total power, and a power factor. The communicationmodule is adapted for transmitting the datagrams using a serialcommunication protocol, wherein the serial communication protocol is atleast one of RS-485, DNP 3.0, 10/100BaseT Ethernet, or Modbus/TCPcommunication protocols.

In yet aspect, a method of presenting a fractional numerical value in adigital data format, includes forming a datagram having a pre-determinednumber of the data segments; and assigning to contents of the datasegments numerical values providing that an average numerical value ofthe contents is equal to the fractional numerical value, wherein thefractional numerical value is an instantaneous numerical value of atleast one parameter of an AC electrical service selected from the groupconsisting of a line voltage, a line current, a phase voltage, a phasecurrent, and a total harmonic distortion (THD) or a root mean square(RMS) value thereof; energy, revenue, real power, reactive power, totalpower, and a power factor. A computer readable medium storing a programcode that, when executed by a computer, facilitates execution of themethod or portions thereof is also provided.

According to another aspect, an intelligent electronic device includes ametering module adapted for measuring or calculating at least oneparameter of an AC electrical service; a processing module adapted foradministering operation of the device and processing data obtained usingthe metering module; and a communication module adapted for coupling toa remote terminal, wherein the communication module includes at leastone communication card coupled to the processing module using one ormore serial data interfaces, wherein the at least one parameter isselected from the group consisting of a line voltage, a line current, aphase voltage, a phase current, and a total harmonic distortion (THD) ora root mean square (RMS) value thereof; energy, revenue, real power,reactive power, total power, and a power factor. The serial datainterfaces include at least one of a RS-485 interface or a SerialPeripheral Interface (SPI). The at least one communication card includesa network communication card adapted for transmitting results ofmeasuring or calculating the at least one parameter and transmitting orreceiving configuration settings of the device, wherein the networkcommunication card is adapted for supporting data exchanges using aRS-485 interface or a DNP 3.0 interface and for transmitting KYZ energypulses. The at least one communication card includes an input/output(I/O) card, wherein the I/O card is selectively adapted for supportingdata exchanges using a 10/100BaseT Ethernet interface, a Modbus/TCPinterface, analog 0-1 mA signals, analog 4-20 mA current loop signals,digital signals, relay contacts, solid-state contacts, or fiber-opticsignals. The communication module further includes an infra-red (IR)communication device.

A method of communicating data using an intelligent electronic deviceadapted for monitoring an AC electrical service is provided. The methodincludes measuring or calculating at least one parameter of the ACelectrical service; and forwarding results of measuring or calculatingthe at least one parameter to a transmitter adapted for supporting dataexchanges using a RS-485 interface, a DNP 3.0 interface, a 10/100BaseTEthernet interface, a Modbus/TCP interface, analog 0-1 mA signals,analog 4-20 mA current loop signals, digital signals, relay contacts,solid-state contacts, or fiber-optic signals, wherein the at least oneparameter is selected from the group consisting of a line voltage, aline current, a phase voltage, a phase current, and a total harmonicdistortion (THD) or a root mean square (RMS) value thereof; energy,revenue, real power, reactive power, total power, and a power factor.

In a further aspect, an intelligent electronic device includes ametering module adapted for measuring or calculating at least oneparameter of an AC electrical service; a processing module adapted foradministering operation of the device and processing data obtained usingthe metering module; and a display adapted for displaying numericalvalues of the at least one parameter, wherein the processing module isadapted for: calculating an average value F₁ of M consecutive datapoints DP₁ through DP_(M) of the at least one parameter, F₁=(DP₁+DP₂+ .. . + DP_(M))/M, where M is a pre-determined integer and M>1;calculating a weighted average F₂ of M+1 consecutive data points DP₁through DP_(M+1) of the at least one parameter, F₂=[(M−1)F₁+DP_(M+1)]/M;if |F₂−DP_(M+1)| is equal to or smaller than a pre-determined constant,displaying on the display the weighted average F₂; and if |F₂−DP_(M+1)|is greater than the pre-determined constant, displaying on the displaythe data point DP_(M+1) and replacing the average value F₁ withDP_(M+1). The at least one parameter is selected from the groupconsisting of a line voltage, a line current, a phase voltage, a phasecurrent, and a total harmonic distortion (THD) or a root mean square(RMS) value thereof; energy, revenue, real power, reactive power, totalpower, and a power factor. A periodicity of calculating the weightedaverage F₂ is substantially greater than a rate of refreshing thedisplay.

In another aspect, a method of displaying on a display a numerical valueof a time-varying parameter includes calculating an average value F₁ ofM consecutive data points DP₁ through DP_(M) of the parameter,F₁=(DP₁+DP₂+ . . . +DP_(M))/M, where M is a pre-determined integer andM>1; calculating a weighted average F₂ of M+1 consecutive data pointsDP₁ through DP_(M+1) of the parameter, F₂=[(M−1)F₁+DP_(M+1)]/M; if|F₂−DP_(M+)1| is equal to or smaller than a pre-determined constant,displaying on the display the weighted average F₂; and if |F₂−DP_(M+1)|is greater than the pre-determined constant, displaying on the displaythe data point DP_(M+1) and replacing the average value F₁ withDP_(M+1), wherein the numerical value of the time-varying parametercomprises a noise component. The method further includes calculating theweighted average F₂ with a periodicity that is substantially greaterthen a rate of refreshing the display. The time-varying parameter is aparameter of an AC electrical service selected from the group consistingof a line voltage, a line current, a phase voltage, a phase current, anda total harmonic distortion (THD) or a root mean square (RMS) valuethereof; energy, revenue, real power, reactive power, total power, and apower factor.

In still another aspect, an intelligent electronic device includes ametering module adapted for measuring or calculating at least oneparameter of an AC electrical service; and a processing module adaptedfor administering operation of the device and processing data obtainedusing the metering module, wherein the processing module is adapted foraveraging numerical values of data points of the at least one parameterhaving same timing relationship in a pre-defined number of consecutiveAC cycles. The processing module is further adapted for averaging thenumerical values of the data points during a pre-determined timeinterval. The at least one parameter is selected from the groupconsisting of a line voltage, a line current, a phase voltage, a phasecurrent, and a total harmonic distortion (THD) or a root mean square(RMS) value thereof; energy, revenue, real power, reactive power, totalpower, and a power factor.

In another aspect, the data points are acquired in the consecutive ACcycles after expiration of same time intervals starting at zero-crossingpoints of said AC cycles, wherein the zero-crossing points are momentsof time when a polarity of the at least one parameter changes from anegative polarity to a positive polarity when a polarity of the at leastone parameter changes from a positive polarity to a negative polarity.In one aspect, the pre-defined number of data points is equal to orgreater than 4.

According to yet another aspect of the present disclosure, a method ofmeasuring an instant numerical value of a cyclically-varying parameterhaving a noise component includes (a) selecting data points of theparameter having same timing relationship in a pre-defined number ofconsecutive cycles of the parameter or during a pre-determined timeinterval; (b) calculating an average numerical value of the data points;and (c) adopting the average numerical value of the data points as theinstant numerical value of the parameter. The data points are acquiredin the consecutive cycles after expiration of same time intervalsstarting at zero-crossing points of said cycles. In one aspect, thepre-defined number of data points is equal to or greater than 4. Thecyclically-varying parameter is a parameter of an AC electrical serviceselected from the group consisting of a line voltage, a line current, aphase voltage, a phase current, and a total harmonic distortion (THD) ora root mean square (RMS) value thereof; energy, revenue, real power,reactive power, total power, and a power factor.

In another aspect, an intelligent electronic device is providedincluding a metering module adapted for measuring or calculating atleast one parameter of an AC electrical service; a processing moduleadapted for administering operation of the device and processing dataobtained using the metering module; a user interface unit adapted fordisplaying results of measuring or calculating the at least oneparameter or configuration settings of the device; and a communicationmodule adapted for coupling to a remote terminal, wherein the device isadapted for: performing calibrating measurements of supply voltages orsupply currents of the AC electrical service in a plurality ofcalibrating points; adjusting gain factors of sensors of the supplyvoltages or the supply currents; forming first measuring channelstime-locked to zero-crossing points of the supply voltages or the supplycurrents and second measuring channels time-locked to pre-determinedmoments of time; presenting a data point of the at least one parameteras a datagram having a plurality of data segments which averagenumerical value is equal to an instantaneous numerical value of the atleast one parameter; averaging numerical values of data points of the atleast one parameter having same timing relationship in a pre-definednumber of consecutive AC cycles or during a pre-determined timeinterval; displaying a pre-determined portion of results of processingthe data; displaying at least a portion of the configuration settings ofthe device; and exchanging information with the remote terminal. The atleast one parameter is selected from the group consisting of a linevoltage, a line current, a phase voltage, a phase current, and a totalharmonic distortion (THD) or a root mean square (RMS) value thereof;energy, revenue, real power, reactive power, total power, and a powerfactor.

The metering module includes a sensing circuit adapted for monitoring atleast a portion of the supply voltages or the supply currents; a dataacquisition system; and a gain control unit adapted for selectivelyadjusting operating ranges of at least a portion of output signals ofthe sensing circuit to match pre-determined ranges for input signals ofthe data acquisition system.

The user interface unit includes a display adapted for displayingalpha-numeric information contained in said instructions; indicators ofthe configuration settings of the device or a relative numerical valueof the at least one parameter; user controls selectively coupled to theprocessing module and adapted for activating functions of the device orentering user commands; and a decoder of instructions received, via aserial data interface, from the processing module.

In another aspect, the communication module includes a networkcommunication card coupled to the processing module using one or moreserial data interfaces and adapted for exchanging data using a RS-485interface or a DNP 3.0 interface and transmitting KYZ energy pulses. Thecommunication module further includes at least one input/output (I/O)card coupled to the processing module using one or more serial datainterfaces and selectively adapted for exchanging data using a10/100BaseT Ethernet interface, a Modbus/TCP interface, analog 0-1 mAsignals, analog 4-20 mA current loop signals, digital signals, relaycontacts, solid-state contacts, or fiber-optic signals.

A method of monitoring a parameter of an AC electrical service using anintelligent electronic device is provided including performingcalibrating measurements of supply voltages or supply currents of the ACelectrical service in a plurality of calibrating points; adjusting gainfactors of sensors of the supply voltages or the supply currents;forming first measuring channels time-locked to zero-crossing points ofthe supply voltages or the supply currents and second measuring channelstime-locked to pre-determined moments of time; presenting a data pointof the parameter as a datagram having a plurality of data segments whichaverage numerical value is equal to an instantaneous numerical value ofthe parameter; averaging numerical values of data points of theparameter having same timing relationship in a pre-defined number ofconsecutive AC cycles or during a pre-determined time interval;displaying a pre-determined portion of results of measuring orcalculating a numerical value of the parameter; displaying at least aportion of the configuration settings of the device; and exchanginginformation with the remote terminal, wherein the parameter is selectedfrom the group consisting of a line voltage, a line current, a phasevoltage, a phase current, and a total harmonic distortion (THD) or aroot mean square (RMS) value thereof; energy, revenue, real power,reactive power, total power, and a power factor.

Various aspects and embodiments of the disclosure are described infurther detail below.

The Summary is neither intended nor should it be construed as beingrepresentative of the full extent and scope of the present disclosure,which these and additional aspects will become more readily apparentfrom the detailed description, particularly when taken together with theappended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of an exemplary digital electrical powerand energy meter in accordance with one embodiment of the presentdisclosure.

FIG. 2 is a schematic diagram illustrating circuit configuration of themeter of FIG. 1.

FIG. 3 is a block diagram of a processing module of the meter of FIG. 1.

FIG. 4 is a block diagram of a DSP module of the meter of FIG. 1.

FIG. 5 is a schematic view of a front panel of the meter of FIG. 1.

FIG. 6 is a schematic diagram of a main assembly of the meter of FIG. 1.

FIG. 7 is a schematic view of a back panel of the meter of FIG. 1.

FIG. 8 is a block diagram of a network I/O card of the meter of FIG. 1.

FIG. 9 is a block diagram of an analog output I/O card of the meter ofFIG. 1.

FIG. 10 is block diagram of a relay/KYZ pulse output I/O card of themeter of FIG. 1.

FIG. 11 is a block diagram of a fiber-optic I/O card of the meter ofFIG. 1.

FIG. 12 is block diagram an IR communication device of the meter of FIG.1.

FIG. 13 is a high-level flow chart of a method of operating the meter ofFIG. 1.

FIG. 14 is a high-level flow chart of a method for performing voltage,current, and frequency calibrations in the meter of FIG. 1.

FIG. 15 is a series of exemplary graphs illustrating the method of FIG.14.

FIG. 16 is a high-level flow chart of a method for ranging supplyvoltages and supply currents in the meter of FIG. 1.

FIG. 17 is a schematic diagram illustrating circuit configuration of ametering module of the meter of FIG. 1.

FIG. 18 is a high-level flow chart of a method for sampling supplyvoltages and supply currents in a metering module of the meter of FIG.1.

FIG. 19 is an exemplary timing diagram illustrating the method of FIG.18.

FIG. 20 is a high-level flow chart of a method for displaying controlledparameters in the meter of FIG. 1.

FIG. 21 is an exemplary timing diagram illustrating the method of FIG.20.

FIG. 22 is a high-level flow chart of a method of averaging data pointsin the meter of FIG. 1.

FIG. 23 is an exemplary timing diagram illustrating the method of FIG.22.

FIG. 24 is a high-level flow chart of a method for providing virtualrelays in the meter of FIG. 1.

FIG. 25 is an exemplary timing diagram illustrating the method of FIG.24.

FIG. 26 is a high-level flow chart of a method for transmittingfractional values of a reported parameter in the meter of FIG. 1.

FIG. 27 is an exemplary timing diagram illustrating the method of FIG.26.

FIG. 28 is a schematic diagram illustrating circuit configuration of auser interface unit of the meter of FIG. 1.

FIG. 29 is a high-level flow chart of a method for verifying energymeasurements of the meter of FIG. 1.

FIG. 30 is a block diagram an exemplary system using the method of FIG.29.

FIG. 31 is a high-level flow chart of a method for configuring functionsand settings of the meter of FIG. 1.

FIG. 32 is a graph illustrating waveform capture performed by the meterof FIG. 1.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures, except that suffixes may be added, when appropriate, todifferentiate such elements. The images in the drawings are simplifiedfor illustrative purposes and are not depicted to scale.

The appended drawings illustrate exemplary embodiments of the presentdisclosure and, as such, should not be considered as limiting the scopeof the disclosure that may admit to other equally effective embodiments.It is contemplated that features or steps of one embodiment maybeneficially be incorporated in other embodiments without furtherrecitation.

In some embodiments, method steps of methods in FIGS. 13, 14, 16, 18,20, 22, 24, 26, 29, and 31 are performed in the depicted order. Inalternate embodiments, in the respective methods, at least two methodsteps or portions thereof may be performed contemporaneously, inparallel, or in a different order.

DETAILED DESCRIPTION

Aspects of the present disclosure are illustratively described hereinwithin the context of digital electrical power and energy meters,including revenue accuracy certifiable meters. The term “digitalelectrical power and energy meters” is broadly used herein in referenceto IEDs adapted to record, measure, or communicate at least some ofsupply currents and supply voltages of the respective electricalservice, their waveforms, harmonics, transients, and other disturbances,and the corresponding parameters, such as power, power quality, energy,revenue, and the like. Moreover, a variety of electrical serviceenvironments may employ IEDs and, in particular, may employ digitalelectrical power and energy meters. By way of example and notlimitation, these environments include power generation facilities(e.g., hydroelectric plants, nuclear power plants, etc.), powerdistribution networks and facilities, industrial process environments(e.g., factories, refineries, etc.), and backup generation facilities(e.g., backup generators for a hospital, a factory, etc.).

It will be appreciated by those skilled in the art that the disclosuremay also be utilized within the context of other IEDs, includingProgrammable Logic Controllers (“PLC's”), Remote Terminal Units(“RTUs”), protective relays, or fault recorders, among other devices orsystems used to manage and control quality, distribution, andconsumption of electrical power.

FIG. 1 depicts a schematic diagram illustrating an exemplary digitalelectrical power and energy meter 100 (referred to hereafter as “meter”)in accordance with one embodiment of the present disclosure. The meter100 generally comprises a metering module 110, a processing module 120,an optional user interface unit 130, a communications module 140, and apower supply 150.

The metering module 110 is coupled to supply lines of electrical service101 (shown in phantom) using current interface 111 and voltage interface113. In the depicted embodiment, the supply lines illustratively includephase lines A, B, and C and a neutral line N. Methods of couplingdigital electrical power and energy meters to various electricalservices are described in detail in U.S. patent application Ser. No.11/003,064, the contents of which are hereby incorporated by reference.As used herein, the term “coupled” is defined to mean directly connectedto or indirectly connected to through one or more intermediatecomponents. Such intermediate components may include both hardware andsoftware based components.

Referring to FIG. 2 and FIG. 17, in one embodiment, the metering module110 comprises a sensing circuit 242 including voltage dividers 1702 (orpotential transformers) and current sensors 1704, a gain control unit244 including voltage and current gain control circuits 1722 and 1724,and a data acquisition system 246 including current analog-to-digitalconverters (ADCs) 1712, voltage ADCs 1714, and a metering processor1710. Components of the metering module 110 are adapted to processsignals corresponding to the supply voltages and currents of the phaselines A, B, and C of the electrical service 101, which are provided tothe sensing circuit 242 via interfaces 113 and 111, respectively.

Using interface 123, the metering module 110 is coupled to theprocessing module 120. In one embodiment, the interface 123 includesSerial Peripheral Interface (SPI) 1711, control interface 1723, voltageand current gain control buses 1717 and 1725, gain-adjusted outputs 1719and 1721 of the circuits 1722 and 1724, an energy test pulse (i.e., KYZpulse) output 1713, and a bus 1715 providing zero-crossing signals ofthe metering processor 1710.

Referring to FIG. 3, in one embodiment, the processing module 120comprises a central processor 310, a digital signal processing (DSP)module 330, a real-time clock 340, a power backup 350 (e.g., replaceablebattery), support circuits 360, and a memory module 320 including arandom access memory (RAM) 322, a flash memory 324, and an electricallyerasable programmable read-only memory (EEPROM) 326. It is to beappreciated that the components of the processing module 120 may bedisposed on a single integrated circuit or arranged over severalintegrated circuits on a printed circuit board.

Referring to FIG. 4, the DSP module 330 includes analog to digitalconverters ADCs 411-414 converting in a digital domain analog outputsignals 1719 and 1721 (shown in FIG. 17) of the metering module 110, afront panel controller 430 (discussed in reference to FIG. 28), and acommunications controller 440.

In one embodiment, the ADCs 411-414 (typically, each such ADC includes adedicated unit for each one of the phases A, B, and C) are used in FastFourier Transform (FFT) analysis (ADCs 411, 413) and waveform analyses(ADCs 412, 414) of the voltages (ADCs 413, 414) and currents (ADCs 411,412) of the electrical service 101. The waveform capture and analysis ofanalog output voltage and current signals 1719 and 1721 will be describebelow in relation to FIG. 32.

In operation, the front panel controller 430 administers data exchangesbetween the processing module 120 and user interface unit 130, and thecommunications controller 440 administers data exchanges between theprocessing module 120 and communications module 140, respectively.

Referring back to FIG. 1, in one embodiment, the user interface unit 130comprises a front panel display 132, a plurality of indicators 134 (forexample, LED indicators), user controls 136, and an IRtransmitter/receiver 540 (discussed in reference to FIG. 12.

Referring to FIG. 5, in one embodiment, the front panel display 132includes a plurality of segments 514 (for example, liquid crystaldisplay (LCD) segments, LED segments, etc.). Each segment 514 is adaptedfor displaying numerals from 0 to 9, at least some letters orrecognizable portions thereof, and a decimal point. The segments 514 arearranged in 3 rows 512 ₁-512 ₃, each row including 4 segments 514.

In the depicted embodiment, the indicators 134 are arranged as groups530 ₁-530 ₃ and a status bar 550. The groups 530 ₁-530 ₃ are composed ofLEDs 532, where each LED identifies a particular kind of data presentedon the front panel display 132. Correspondingly, the status bar 550includes a plurality of LEDs arranged to indicate a numerical orrelative value of a pre-selected parameter that is monitored orcalculated by the meter 100.

The user controls 136 generally include multi-functional pushbuttons 520₁-520 ₄ allowing to select particular data of interest for being shownon the front panel display 132, confirm configuration settings of themeter 100, or review status messages generated by the meter.

In one exemplary embodiment, the LED indicators 532 correspond to thefollowing properties: “VOLTS L-N”, “VOLTS L-L”, “Amps”, “W/VAR/PF”,“Wh”, “VARh” (block 530 ₁); “MAX”, “MIN”, “LM1”, LM2”, % THD”, “PRG”(block 530 ₂); and “Wh Pulse”, “KILO”, “MEGA” (block 530 ₃), whereabbreviations “L-N”, “L-L”, “PF”, “LM”, “THD”, and PRG” refer to theterms “line-to-neutral”, “line-to-line”, power factor”, “limit”, “totalharmonic distortion”, and “programming mode”, respectively. In thisembodiment, the status bar 550 shows an amount, in percents, of consumedelectrical power versus a pre-determined limit, and the “MENU”, “ENTER”,“▾” (i.e., “Scroll Down”), and “

” (i.e., “Select”) pushbuttons 520 are selectively used to activatefunctions or configuration settings of the meter 100.

In other embodiments, the meter 100 may comprise the display 132 havinga different configuration (e.g., different number of segments 514), aswell as the LED indicators 532 may correspond to different parameters orproperties. In other embodiments, the display 132, indicators 134 anduser controls 136 may be configured as a single touch screen.

Referring back to FIG. 1, in one embodiment, the communications module140 comprises a network communication card 142, a plurality of optionalinput/output (I/O) cards 144 ₁-144 _(N), where N is an integer, and aninfra-red (IR) communication device 146. Each meter 100 may beconfigured to include up to two of the same or different I/O cards 144.

The power supply 150 provides power to components of the meter 100 andtypically is coupled, via interface 151, to an external power source(not shown) or, alternatively or additionally, to the voltage interface113 (shown with interface 153).

Referring to back FIG. 2, in one embodiment, the meter 100 includes amain printed circuit board (PCB) 210, an input PCB 220, the networkcommunication card 142, e.g., a RS-485 card, and, optionally, one or twoI/O cards 144.

The main PCB 210 generally contains the processing module 120, the userinterface unit 130, and the IR communication device 146. Accordingly,the input PCB 220 generally contains the metering module 110 and thepower supply 150.

The input PCB 220, network communication card 142, and I/O cards 144 arecoupled to connectors 214, 216, and 218 ₁-218 ₂ of the main PCB 210using the mating input connectors (for example, plug-in connectors) 241,222, and 226 ₁-226 _(N), respectively. In particular, any of the I/Ocards 144 may be coupled to the connector 218 ₁ or the connector 218 ₂.

The input PCB 220 is provided with a connector 232 for coupling to thevoltage interface 113 and interface 151 and includes a means 234 forcoupling to the current interface 111.

Correspondingly, the network communication card 140 and I/O cards 144₁-144 _(N) include output connectors 224 and 228 ₁-228 _(N),respectively, to provide connectivity between the meter 100 and externalcircuits (not shown).

Referring to FIG. 6, in one embodiment, the processing module 120 andconnectors 241, 216, and 218 ₁-218 ₂ are disposed on one surface of themain PCB 210 (illustratively, on surface 610), while the user interfaceunit 130 and the IR communication device 146 are disposed on opposingsurface 620 of the PCB (all components are shown in phantom).Alternatively, portions of the processing module 120 or the IRcommunication device 146 may be disposed on the opposite surfaces of themain PCB 210.

Referring to FIG. 7, in one embodiment, a rear panel 700 of the meter100 (shown in phantom) includes the connectors 232 and 224, openings710, 712 for the I/O cards 144 (illustratively, cards 144 ₁ and 144 ₂are shown), and a status display 720. Vacant openings for the I/O cards144 may be sealed using protective covers (not shown). The statusdisplay 720 generally includes LEDs 722 and 724 indicating a currentdirection of data transmission (i.e., incoming (RX) or outgoing (TX)data transmission) via the network communication card 142.

Exemplary I/O cards 144 include a 10/100BaseT Ethernet I/O card 144 ₁,analog I/O cards 144 ₂ and 144 ₃, relay I/O cards 144 ₄ and 144 ₅, and afiber-optic I/O card 144 ₆. In one embodiment, the I/O cards 144 arecoupled to the processing module 120 using one or more serialinterfaces, for example, SPI interface.

Referring to FIG. 8, each of the network communication card 142 or the10/100BaseT Ethernet I/O card 144 ₁ (collectively denoted using anumeral 800) generally includes a serial Universal AsynchronousReceiver/Transmitter (UART) 810, a co-processing unit 812, and an EEPROM814. In one embodiment, the network communication card 142 supportsRS-485, Modbus and DNP 3.0 communication protocols, or interfaces, andwhereas the 10/100BaseT Ethernet I/O card 144 ₁ supports the 10/100BaseTEthernet and Modbus/TCP communication protocols.

Referring to FIG. 9, each of the analog I/O cards 144 ₂ and 144 ₃(collectively denoted using a numeral 900) generally includes the UART810, a co-processing module 912, and an EEPROM 914. In one embodiment,the I/O card 144 ₂ supports standard bi-directional 0-1 mA signals, andthe I/O card 144 ₂ supports standard 4-20 mA current loop signals.

Referring to FIG. 10, each of the relay I/O cards 144 ₄ and 144 ₅(collectively denoted using a numeral 1000) generally includes the UART810, a relay block 1012, and an EEPROM 1014. In one embodiment, therelay I/O cards 144 ₄ and 144 ₅ provide digital inputs and a pluralityof output ON/OFF contacts (card 144 ₃) and a plurality solid-stateoutput contacts (card 144 ₄).

Referring to FIG. 11, the fiber-optic I/O card 144 ₆ (collectivelydenoted using a numeral 1100) generally includes the UART 810, afiber-optic receiver/transmitter 1112, an EEPROM 1114, and an echoswitch 1116. In operation, the echo switch 1116 allows incoming messagesto bypass the meter 100, thus enabling the meter for use in networkshaving daisy-chain configurations.

Referring to FIG. 12, the IR communication device 146 generallycomprises the IR transmitter/receiver 540 and a controller 1210including the UART 810 and an EEPROM 1214. In one embodiment, the IRcommunication device 146 supports a bi-directional IR communication linkwith an external IR-enabled communication device (not shown), such as aPersonal Digital Assistant (PDA), and the like.

Hereafter, the terms V_(S) and I_(S) are collectively used to designatesupply voltages and supply currents of the phases A, B, and C of theelectrical service 101.

FIG. 13 depicts a high-level flow diagram of a method 1300 of operatingthe meter 100 of FIG. 1 in accordance with one embodiment of the presentdisclosure. To best understand the disclosure, the reader should torefer to FIG. 13 and FIGS. 1, 17 simultaneously.

At step 1310, the supply voltages V_(S) and supply currents I_(S) aresensed using the respective voltage dividers 1702 and currents sensors1704 of the sensing circuit 242 (shown in FIG. 17) of the meteringmodule 110.

At step 1320, gain factors of the voltage dividers 1702 and currentssensors 1704 are adjusted to pre-determined ranges using the voltage andcurrent gain control circuits 1722 and 1724, respectively, of the gaincontrol unit 244 of the metering module 110 (discussed in reference toFIG. 16).

At step 1330, output signals of the voltage dividers 1702 and currentssensors 1704 are digitized in the metering module 110 and, using ADCs411-414, in the DSP module 330 of the processing module 120.

At step 1340, the meter 100 determines the supply voltages V_(S) andsupply currents I_(S) and performs energy/revenue calculations. In oneembodiment, these measurements are performed using a frequency-lockedmeasuring scheme (discussed in reference to FIG. 19 and FIG. 23).

At step 1350, the meter 100 performs harmonic analysis of waveforms ofthe supply voltages V_(S) and supply currents I_(S). In one embodiment,the harmonic analysis is performed using a time-locked measuring scheme(discussed in reference to FIG. 23).

At step 1360, the results of steps 1340 and 1350 are selectivelydisplayed on the front panel display 132 and/or, using thecommunications module 140, forwarded to the respective addressee of themeter 100.

FIG. 14 depicts a high-level flow chart of a method 1400 for performingvoltage, current, and frequency calibrations in the meter 100 of FIG. 1in accordance with one embodiment of the present disclosure, and FIG. 15depicts exemplary graphs 1510 and 1520 illustrating the method 1400. Tobest understand the disclosure, the reader should to refer to FIGS.14-15 simultaneously.

Referring to FIG. 15, the graphs 1510 and 1520 depict calibration traces1505 and 1507 for voltage V and current I (y-axes 1501 and 1502,respectively) as functions of a reference voltage V_(R) and a referencecurrent I_(R) (aggregated x-axis 1504). The traces 1505 and 1507 areselectively accumulated at first and second pre-determined ACfrequencies F₁ and F₂, respectively.

At step 1410, gain factors of components of the meter 100 and, inparticular, the measuring module 110, are calibrated at a plurality ofpre-determined test points (i.e., reference voltages V_(R) and currentsI_(R)), which are disposed in the respective application ranges of themeter 100 (illustratively, voltage test points 1511-1514 (graph 1510)and current test points 1521-1524 (graph 1520) are shown).

In one exemplary embodiment, the test points correspond to the referencevoltages V₁=69V, V₂=120V, V₃=220V, and V₄=480V and reference currentsA₁=250 mA, A₂=500 mA, A₃=1 A, and A₄=5 A at the first pre-determined ACfrequency F₁=50 Hz. Accuracy of calibrations may be about 0.2% orgreater. Generally, certified sources of reference voltages and currentsare used to perform such calibrations.

At step 1420, the same calibration routine is repeated at the secondpre-determined AC frequency F₂=60 Hz.

At step 1430, in operation, during measurements of the voltages V_(S) orcurrents I_(S), their respective values are defined by linearlyinterpolating calibration data for numerically adjacent test points asmeasured at the AC frequencies F₁ and F₂. For example, a value of aparticular supply voltage V_(X), where V₁<V_(X)<V₂ (or particular supplycurrent I_(X), where I₁<I_(X)<I₂) having an AC frequency F_(X), whereF₁<F_(X)<F₂, is determined using linear interpolation equations fornominal values of the numerically adjacent test points 1511 and 1512 (or1521 and 1522) that, additionally, are similarly frequency-interpolated.

Using the method 1400, the meter 100 may be calibrated, withpre-determined accuracy, in all operating ranges of the electricalservice 101. The results of calibrating the meter 100 may be stored inthe EEPROM.

FIG. 16 depicts a high-level flow chart of a method 1600 for rangingsupply voltages V_(S) and supply currents I_(S) in the meter 100 of FIG.1 in accordance with one embodiment of the present disclosure, and FIG.17 is a schematic diagram illustrating the method 1600. To bestunderstand the disclosure, the reader should to refer to FIG. 16-17simultaneously.

At step 1610, the meter 100 assesses nominal values of the supplyvoltages V_(S) and currents I_(S) measured using the metering module110. These values may be determined using the processing module 120 or,alternatively, using the metering processor 1710 of the metering module110.

At step 1620, the meter 100 determines an industry-standard nominalvalue of the supply voltage V_(S) (for example, 69V, 120V, 230V, 277V,347V, 416V, 721V, etc.) and a nominal range for the supply currentsI_(S) (for example, 0-1 A, 0-5 A, or 0-10 A).

At step 1630, gain factors of the voltage dividers 1702 and currentsensors 1704 are adjusted using voltage and current gain control circuit1722 and 1724, respectively. In the depicted embodiment, the circuit1722 and 1724 are controlled using respective signals of the voltage andcurrent gain control buses 1717 and 1725. In an alternate embodiment(shown in phantom using links 1731 and 1733), the circuit 1722 and 1724may be controlled using the respective output signals generated by themetering processor 1710.

After such gain adjustments, regardless of actual values of the supplyvoltages V_(S) and supply currents I_(S) of the electrical service 101,output signals of the circuit 1722 correspond to a pre-selectedindustry-standard range ΔV for the supply voltages V_(S) (for example,0-120V), and output signals of the circuit 1724 correspond to apre-selected range ΔI for the supply currents I_(S) (for example, 0-2A).

Gain adjustments for the supply voltages and currents may be performedin a real time (i.e., dynamically) or, alternatively, gain factors ofthe circuit 1722 or circuit 1724 may be pre-configured based on knowncharacteristics of the electrical service 101 or electrical load, whichpower consumption is monitored using the meter 100. In operation,procedures of step 1630 allow to perform measurements of the voltagesV_(S) and supply currents I_(S), regardless of their nominal values,with the same high accuracy in the respective operating ranges of themeter 100.

In some embodiments, the circuit 1722 and 1724 comprise separategain-controlled amplifiers for each phase of the electrical service 101.Alternatively, each of the circuits 1722 and 1724 may include one suchamplifier and multiplexers/de-multiplexers of the gain-controlledsignals.

At step 1640, the meter 100 processes output signals of the circuit 1722and 1724.

At step 1650, the meter 100 re-calculates the results of measurementsand calculations performed using output signals of the circuit 1722 and1724 to compensate for the gain adjustments of step 1630. There-calculated data for the actual values of the supply voltages V_(S),supply currents I_(S), energy, revenue, and other monitored or measuredparameters and properties is then selectively displayed on the frontpanel display 132 or, using the communications module 140, forwarded tothe respective addressee of the meter 100.

FIG. 18 depicts a high-level flow chart of a method 1800 for samplingsupply voltages V_(S) and supply currents I_(S) in the metering module110 of the meter 100 of FIG. 1 in accordance with one embodiment of thepresent disclosure, and FIG. 19 is an exemplary timing diagramillustrating the method 1800. To best understand the disclosure, thereader should to refer to FIGS. 18-19 and FIG. 17 simultaneously.

Referring to FIG. 19, a graph 1900 depicts a cycle of an exemplarywaveform 1901 of the supply voltage V_(S) (or supply current I_(S))(y-axis 1902) as a function of time (x-axis 1904). Illustratively, thewaveform 1901 is digitized at cyclically repeated moments T0-T11, andthe corresponding data points are collectively denoted herein using areference numeral 1912.

At step 1810, the supply voltages V_(S) and supply currents I_(S) aresensed using the voltage dividers 1702 and currents sensors 1704 of thesensing circuit 242 (shown in FIG. 17) of the metering module 110.

At step 1820, the gain factors of the voltage dividers 1702 and currentssensors 1704 are adjusted as discussed in reference to the method 1600of FIG. 16.

At step 1830, the metering module 110 generates zero-crossing signals1715 (shown in FIG. 17) for the supply voltages V_(S) and supply currentI_(S). In one embodiment, the metering module 110 detects moments oftime when polarity of the waveform 1901 changes from negative topositive (i.e., when the rising waveform 1901 crosses the x-axis 1904).Such moments are referred to herein as zero-crossing points and, in FIG.19, are denoted as T0. A zero-crossing signal is a pulse signal (notshown) time-locked to a zero-crossing point. In one embodiment, aleading edge of the zero-crossing signal coincides, in each cycle of thewaveform 1901, with the moment T0. In an alternate embodiment, thezero-crossing points may refer to the moments when polarity of thewaveform 1901 changes from positive to negative (i.e., the moments T6).

At step 1840, the ADCs 1714, 1712 of the data acquisition system 246 inthe metering module 110 are synchronized using the zero-crossing signals1715 (shown in phantom with links 1703, 1705 in FIG. 17). Similarly, thezero-crossing signals 1715 are used to synchronize the ADCs 411-413 inthe DSP module 330.

At step 1850, gain-adjusted output signals of the dividers 1702 andcurrents sensors 1704 are digitized using voltage ADCs 1714 and currentADCs 1712, respectively. The digitized gain-adjusted output signals usedin the data acquisition system 246 to measure the supply voltages V_(S)and supply current I_(S).

Generally, a sampling rate of the ADCs 1714 and 1712 may be in rangefrom about 12 to 36 KHz, which corresponds to about 200-600 data pointsper a cycle of the waveform 1901 at the AC frequency of 60 Hz. In oneexemplary embodiment, the sampling rate is about 26 KHz.

FIG. 20 depicts a high-level flow chart of a method 2000 for displayingcontrolled parameters in the meter 100 of FIG. 1 in accordance with oneembodiment of the present disclosure, and FIG. 21 is an exemplary timingdiagram 2100 illustrating the method 2000. To best understand thedisclosure, the reader should to refer to FIGS. 20-21 simultaneously.

Referring to FIG. 21, the timing diagram 2100 depicts pluralities ofdata points 2110, 2120, and 2130 and data points 2101 and 2103, whereeach of these data points corresponds to a value (y-axis 2102) of anarbitrary parameter P1 displayed on the front panel display 132 as afunction of time (x-axis 2104).

At step 2010, in operation, the meter 100 accumulates a pre-determinednumber M of consecutive data points DP₁ through DP_(M) of the parameterP1, where M>1. Examples of such parameters include supply voltagesV_(S), supply currents I_(S), energy, or revenue, among other parametersand properties discussed in reference to FIG. 5.

At step 2020, an average value F₁ of the data points DP₁ through DP_(M)of the parameter P1 is calculated, F₁=(DP₁+DP₂+ . . . +DP_(M))/M.

At step 2030, a weighted average F₂=[(M−1)F₁+DP_(M+1)]/M is calculated,where DP_(M+1) is a consecutive (M+1) data point of the parameter P1.

At step 2040, the method 2000 queries if |F₂−DP_(M+1)| is equal tosmaller than a pre-determined value, or limit, A (i.e., if|F₂−DP_(M+1)|≦A).

If the query of step 2040 is affirmatively answered, the method 2000proceeds to step 2050, where a value of the weighted average F₂ isdisplayed on the front panel display 132. Referring to FIG. 21, thiscondition is met during time intervals 2111, 2121, and 2131.

If the query of step 2040 is negatively answered, the method 2000proceeds to step 2060, where a value of the data point DP_(M+1) isdisplayed on the front panel display 132 and adopted as the new averagevalue F₁ in calculations of consecutive values of the weighted averageF₂ for data points accumulated after the data point DP_(M−1). Referringto FIG. 21, this condition is met at the data points denoted usingreference numerals 2101 and 2103.

In operation, the method 2000 allows to filter digital noise associatedwith measurements of the displayed parameters P1. Due to high rates ofmeasuring and calculating parameters of interest in the meter 100, thereare no interruptions in displaying such data on the display 132. Inparticular, a periodicity of calculating a consecutive value of theweighted average F₂ is substantially greater then a refreshing rate ofthe display 132. In one embodiment, using the communications module 140,the meter 100 transmits to the respective addressee the values displayedon the front panel display 132. Alternatively, the meter 100 transmitsvalues of the data points DP.

FIG. 22 is a high-level flow chart of a method 2200 for averaging datapoints in the meter 100 of FIG. 1 in accordance with one embodiment ofthe present disclosure, and FIG. 23 is an exemplary timing diagram 2300illustrating the method 2200. To best understand the disclosure, thereader should to refer to FIGS. 22-23 and FIG. 19 simultaneously.

Referring to FIG. 23, the timing diagram 2300 depicts a waveform 2310 ofthe supply voltage V_(S) (or supply current I_(S)) (y-axis 2302) as afunction of time (x-axis 2304). Illustratively, to show impact of analognoise associated with the waveform 2310, the waveform is depicted as aband having noise-defined boundaries 2310 _(A) and 2310 _(B). At anymoment of time, a measured value of the supply voltage V_(S) (or supplycurrent I_(S)) is disposed in the respective portion of such a band. Inthe depicted embodiment, data points 2316 _(A)-2316 _(D) are measured atexemplary moments t_(A)-t_(D) corresponding to the same phase angles intheir respective AC cycles, and their values are randomly disposed in arange 2312 defined by the boundaries 2310 _(A) and 2310 _(B).

At step 2210, zero-crossing points 2306 of the waveform 2310 are definedas discussed in reference to FIGS. 18-19 and the waveform is digitized,or sampled.

At step 2220, during consecutive AC cycles 2320 of the waveform 2310(four AC cycles A-D are shown), pluralities of data pointscorresponding, in the respective AC cycles, to the same phase angles areselectively measured and identified. Such data points are disposed, onthe x-axis 2304, at the same distances from the correspondingzero-crossing points 2306. For example, in the depicted embodiment,corresponding to the same phase angles data points 2316 _(A)-2316 _(D)are disposed, in their respective AC cycles, at the same distances 2314away from the zero-crossing points 2306.

At step 2230, values Q of the data points 2316 _(A)-2316 _(D) areaveraged for a predetermined number m of the waveform 2310 (for example,in the depicted embodiment, values Q₁-Q₄ of four data points 2316_(A)-2316 _(D) are averaged). Then, the averaged values Q_(AVE) of thedata points are used in the V_(S) (or I_(S)) based calculationsperformed in the metering module 110 or the processing module 120. Inoperation, such averaging of values of consecutive data pointscorresponding to the same phase angles allows to suppress analog noisein the measurements of the supply voltages V_(S) and supply currentsI_(S) approximately by a factor of {(Q₁)²+(Q₂)²+ . . . +(Q_(m))²}^(1/2).

At step 2240, averaging is performed during a pre-determined timeinterval 2340. In one embodiment, the results of step 2240 are used inthe processing module 120 during harmonic analysis (for example,measurements of total harmonic distortion (THD)) of waveform of thesupply voltages V_(S) and currents I_(S). Typically steps 2220, 2230 and2240 are performed using the DSP module 330 of the processing module120.

FIG. 24 depicts a high-level flow chart of a method 2400 for providingvirtual relays in the meter 100 of FIG. 1 in accordance with oneembodiment of the present disclosure, and FIG. 25 is an exemplary timingdiagram 2500 illustrating the method 2400. To best understand thedisclosure, the reader should to refer to FIGS. 24-25 simultaneously.

Referring to FIG. 25, a graph 2510 depicts a value (y-axis 2502) of aparticular controlled (i.e., monitored or calculated) parameter P2 bythe meter 100 as a function of time (x-axis 2504). Examples of theparameters P2 include supply voltages V_(S), supply currents I_(S),energy, or revenue, among other parameters and properties discussed inreference to FIG. 5.

At step 2410, values of pre-determined constants, or limits, associatedwith the controlled parameter P2 (illustratively, values 2513 (upperlimit) and 2511 (lower limit)) are saved in the meter 100. Such limitsmay be entered during a process of configuring the meter 100.Alternatively, in operation, the limits may be communicated to the meter100 via the communications module 140.

At step 2420, the meter 100 measures or calculates values of theparameter P2. In one embodiment, the meter uses method 2200 (discussedin reference to FIG. 22) to reduce noise associated with suchmeasurements.

At step 2430, the meter 100 detects events when a value of the parameterP2 reaches the pre-determined limits (in FIG. 25, the limits 2513 and2511 are reached at moments 2515 and 2717, respectively).

At step 2440, via the communications module 140, the meter 100 reportsthe detected events to a respective addressee of the meter 100.

In operation, the meter 100 may similarly monitor a plurality ofarbitrary parameters each having a unique set of per-determined limits.

FIG. 26 depicts a high-level flow chart of a method 2600 fortransmitting fractional values of an arbitrary reported parameter P3 inthe meter 100 of FIG. 1 in accordance with one embodiment of the presentdisclosure, and FIG. 27 is an exemplary timing diagram 2700 illustratingthe method 2600. To best understand the disclosure, the reader should torefer to FIGS. 26-27 simultaneously.

Referring to FIG. 27, a graph 2710 depicts a plurality of datagrams 2720(datagrams 2720 _(A)-2720 _(E) are shown) of the parameter P3. Eachdatagram includes a pre-determined number of data segments (in thedepicted embodiment, each of the datagrams 2720 _(A)-2720 _(E) includesfour data segments 2722 ₁-2722 ₄). Exemplary numerical values NV (y-axis2702) of the data segments 2722 ₁-2722 ₄ are shown as a function of time(x-axis 2704). Examples of the parameters P3 include supply voltagesV_(S), supply currents I_(S), energy, or revenue, among other parametersand properties discussed in reference to FIG. 5.

At step 2610, data points of the parameter P3 are measured or calculatedin the meter 100. In one embodiment, the data points are defined withaccuracy that exceeds binary resolution supported by the communicationsmodule 140 or the respective addressee of the meter 100.

At step 2620, a datagram 2720 is assembled and transmitted to therespective addressee.

When a value of a data point to be transmitted is a number that candirectly be transmitted by the communications module 140 or recognizedby the addressee of the meter 100 (for example, numerical values NV₁ orNV₂), all data segments 2722 of the respective datagram 2720 have thatvalue. For example, the datagrams 2720 _(A) and 2720 _(E) include thedata segments 2722 ₁-2722 ₄ having only the values NV₁ and NV₂,respectively.

To transmit a fractional value NV_(X) that can't be directly betransmitted by the communications module 140 or recognized by theaddressee of the meter 100, a value of one or more segments 2722 in therespective datagram 2720 is selected such that an average numericalvalue of the component data segments is equal to the fractional valueNV_(X).

For example, when a difference between the NV₂ and NV₁ is equal to 1 bit(i.e., NV₂−NV₁=1 bit), the datagrams 2720 _(B), 2720 _(C), and 2720 _(D)may be used to transmit fractional, in units of bits, numerical valuesNV_(B)=(0.25)+NV₁, NV_(B)=(0.5)+NV₁, and NV_(B)=(0.75)+NV₁,respectively. In this example, the method 2700 allows transmittingnumerical values of the reported parameter P3 in ¼ of a bit increments,thereby effectively increasing accuracy of the transmitted data by afactor or four. In other embodiments, the datagrams 2720 may include adifferent number of data segments 2722 or, in a datagram, numericalvalues of the data segments 2722 may differ by more than 1 bit.

FIG. 28 is a schematic diagram illustrating circuit configuration of theuser interface unit 130 of the meter of FIG. 1.

In the depicted embodiment, the front panel controller 430 of the DSPmodule 330 (discussed in reference to FIGS. 3-4) is connected to adecoder 2810 of the user interface unit 130 and user controls 136 usingbuses 2802 and 2804, respectively. Generally, the bus 2802 includesserial interface (for example, SPI and the like), and a bus 2804includes a plurality of lines that selectively initiate particularfunctions of the meter 100.

In one embodiment, in operation, data carried by the serial interface ofthe bus 2802 is de-multiplexed in the decoder 2810 that, via displayinterface 2812 and indicators interface 2814, selectively outputs thede-multiplexed data to the front panel display 132 and indicators 134.

The display interface 2812 comprises lines carrying signals that (i)enable, or “select”, the addressed segment 514, and (ii) energize, inthe addressed segment 514, sub-segments forming, together, a visibleimage of a requested alphanumerical symbol. Accordingly, the indicatorsinterface 2814 comprises lines carrying signals that enable and energizeone or more of the addressed LEDs.

FIG. 29 depicts a high-level flow chart of a method 2900 for verifyingenergy measurements of the meter 100 of FIG. 1 in accordance with oneembodiment of the present disclosure, and FIG. 30 is a block diagram ofan exemplary system 3000 using the method 2900.

Referring to FIG. 30, in one embodiment, the system 3000 includes themeter 100, an energy standard 3010 (for example, legacyelectro-mechanical energy meter), and a data processor 3020. Inoperation, the meter 100 and energy standard 3010 monitor energyconsumption (shown with links 30101 and 3003, respectively) by a load3004 of the electrical service 3002 (both are shown in phantom).

At step 2910, the energy standard 3010 and the meter 100 under testmonitor for a pre-determined duration of time energy consumption by theload 3004.

At step 2920, the energy standard 3010 and meter 100 communicate resultsof energy measurements in a form of industry-standard KYZ pulses.

At step 2930, the result of the measurements are processed by the dataprocessor 3020 that determines accuracy of the meter 100 versus theenergy standard 3010.

FIG. 31 is a schematic diagram 3100 illustrating programmable featuresof the meter 100 of FIG. 1. The meter 100 may operate in fourprogrammable modes: an Operating Mode 3110, a Reset Demand Mode 3120, aReset Energy Mode 3130, and a Configuration Mode 3140.

A user may cyclically switch between the modes (shown with a link 3141)and independently program settings for each mode by using the usercontrols 136 or via the communication unit 140. Each mode is associatedwith multiple configuration screens that allow the user to select,enter, or modify particular settings (for example, configuration orcommunications settings, limits discussed in reference to FIGS. 24-25,and the like).

In particular, the Reset Demand Mode 3120 and Reset Energy Mode 3130allow the user to disable (delete) pre-existing configuration settingsand reset energy counters of the meter, respectively. Accordingly, inthe Configuration Mode 3140, the user may program functions and settingsof the meter 100 that, in the Operating Mode 3110, are executedaccording to user's instructions.

In a further embodiment of the present disclosure, the IED, e.g.,electrical power meter, will perform waveform capture and logging of themonitored voltage and current waveforms based on various triggers, aswill be described below. It is to be appreciated that the waveformcapture functionality may be implemented in software, firmware and/orhardware, as described above, and includes the following features:

-   -   2048 samples per capture for each of the 6 channels, e.g., Van,        Vbn, Vcn, Ia, Ib. Ic; all channels logged all the time    -   User-set sample rate    -   User-set pre-trigger    -   PQ (i.e., Power Quality) events monitored include Voltage Surge        & Sag and Current Surge    -   Events based on RMS for 1 cycle, updated every half cycle    -   Events based on adaptive RMS    -   Events based on wave shape    -   User-set PQ event thresholds with individual enables for each        event for each channel    -   PQ events cross-referenced to captured waveform data    -   Capture triggers selected from the enabled PQ events    -   Minimum of 2 back-to-back captures guaranteed if a second        trigger occurs    -   Capture trigger via Modbus

The various features and parameters of the waveform capture and loggingfunctionality are user programmable, for example:

-   -   Sample Rate (@nominal 60 Hz)        -   32, 64, 128, 256, 512 are standard        -   1024 is enabled via V-switch technology as disclosed in U.S.            Pat. No. 7,184,904, the contents of which are incorporated            by reference        -   user selects one    -   Number of Pre-trigger Cycles (@nominal 60 Hz)        -   anything from 1 to all but 1    -   RMS Trigger        -   for WYE, applies to Van, Vbn, Vcn, Ia, Ib, Ic        -   for DELTA2CT, applies to Vab, Vbc, Vca, Ia, Ic        -   for 2.5ELEMENT, applies to Van, Vcn, Ia, Ib, Ic        -   specified as % full scale        -   each voltage channel has 2 thresholds (surge & sag)        -   each current channel has 1 threshold (surge)        -   calculated every cycle        -   calculated every half cycle using samples for a whole cycle        -   user selects which channels to enable and sets their            threshold percentages    -   Adaptive RMS Trigger        -   applies to voltage channels for the particular hookup        -   specified as % full scale (same as plain RMS trigger)            -   based on RMS measured by power chip and averaged over 10                minutes        -   no triggers for first 10 minutes        -   each voltage channel has 2 thresholds (surge & sag)        -   trigger calculated every half cycle using samples for a            whole cycle        -   user selects which channels to enable and sets their            threshold percentages        -   all 3 voltage channels use the same kind of RMS triggers            (all are plain or all are adaptive)    -   Wave Shape Trigger        -   applies to voltage channels for the particular hookup        -   specified as % full scale, defines a window above and below            waveform        -   not standard, enabled via V-switch        -   can be set in addition to either RMS trigger        -   user selects which channels to enable and sets a threshold            for each    -   Manual Trigger        -   user writes the password to a Modbus register to force a            trigger        -   no user setting needed

The IED firmware design reserves 32K words of RAM, e.g., RAM 322 asshown in FIG. 3, to support waveform capture and logging. The waveformcapture design allocates this memory as 4 buffers:

-   -   Frequency-locked sample buffer. Also used for THD (i.e., total        harmonic distortion), this holds 256 samples per cycle for 2        cycles on each of the 6 channels. [256*6 channels*2=3072]    -   RMS buffer. This holds the results of the RMS and waveshape        calculations for each channel every [half] cycle, thus forming a        historical record extending back in time. We use it to postpone        capture trigger evaluation until the capture is guaranteed to be        complete. [(6 RMS values+1 tag+1 flag word)*˜140 half cycles@65        Hz=1120]    -   Time-locked sample buffer. This is the large buffer that holds        waveform samples, also called the capture buffer. The time        locked ADC ISR stores incoming samples in this buffer at the        user defined sample rate. It is sized to hold 1 complete capture        plus a generous margin for synchronization and pipeline delays.        RMS and wave shape calculations occur on the [half] cycle using        this buffer's data. [2048*6 channels=12288+predetermined margin]    -   Auxiliary buffer. This buffer holds a capture while it is being        written to flash. It is sized to hold 1 complete capture plus        some overhead for summary or split records. [12288 sample        data+(512+6) summary record=12806]

Referring to FIG. 32, operation of the waveform capture is illustrated.The three voltage channels and three current channels are continuouslysampled and sent to the frequency-locked sample buffer and time-lockedsample buffer. The analog voltage and current signals are received vialines 1719 and 1721 in the DSP module 330. Synchronization between the 2sample buffers, i.e., the frequency-locked sample buffer and time-lockedsample buffer, is accomplished via tags. When storing the lastfrequency-locked sample of each half cycle, a snapshot of thetime-locked sample buffer's index is saved. This tag goes into the RMSbuffer along with its associated RMS values. FIG. 32 illustrates how thebuffers relate to each other, to time, and to input signals of variousfrequencies. It uses 128 samples per second with three (3) 60 Hz cyclesof pre-trigger and has a uniform time axis. Tags are represented by thearrows pointing to the samples buffer. Processing on the half cycle isillustrated although it is in within the scope of the present disclosureto use full cycles, which would changes the buffer depth but not theoverall method.

Referring to FIG. 32, four waveforms are shown. The top one is 60 Hz andserves as the reference for the user-set pre and post trigger values.The other 3 represent incoming data at 3 different frequencies, 45 Hz &65 Hz because these are the design limits, and 50 Hz because it is atypical likely value along with 60 Hz. The middle gray line representsthe trigger as denoted in the figure. The other 2 gray lines are thebeginning and end of a capture, which includes 2048 samples for each ofthe six (6) channels.

The trigger cycle is the one that ends at the middle line denoted astrigger in FIG. 32. The user selects the pretrigger as a number of 60 Hzcycles that precede this line, 3 in this example. 3 cycles at 60 Hz is50 msec. The user also sets the sample rate as a number of samples per60 Hz cycle. This is 128 in this example. 128 samples per 60 Hz cycle is0.13 milliseconds per sample, so a capture of 2048 samples represents267 milliseconds. Thus the user has set up his capture to show 50 ms ofdata before the trigger and 217 ms after for a total of 267 ms.

The arrows pointing down from the 60 Hz reference signal represent halfcycles. The arrows pointing up from the 3 incoming data streams aretheir half cycle points. These are significant because all processingoccurs on the half cycle of the incoming signal. Because we deferchecking for triggers until all data for a possible capture is presentin the buffers, the decision that the trigger occurred happens not atthe gray line but rather at the dotted line on the right that delineatesthe shaded area, i.e., trigger detected and capture performed. Thecorresponding dotted line on the left shows what data is in the buffersat that instant in time. The data saved for the capture will fallbetween the 2 outer gray lines regardless, i.e., begin capture and endcapture, but the internal memory arrangement is able to handle anyfrequency without knowing ahead of time what the frequency will be.

As sample data arrives, RMS is calculated for each cycle (or half cycle)and saved in a FIFO buffer. At the time of evaluation (right dottedline), the RMS value for the trigger cycle is at a known point in theRMS FIFO. In the depicted example, this is exactly 29. On all 4waveforms, there are 29 arrows from trigger to detection point.

The chosen configuration (e.g., 128 samples per second and 3 pretriggercycles) equates to 50 msec pre-trigger and 217 msec post-trigger or 267msec overall. Note that at 65 Hz, there are 3.25 cycles in thepre-trigger interval and 14.08 in the post. This sets the parameters forevaluation. The processing forms a pipeline in which evaluation occurson the half cycle. Each half cycle, the RMS buffer item 29 half cyclesback in time is evaluated for a trigger condition. Timing of thisactivity is delineated by the seam between past (unshaded section) andfuture (shaded section) times. If a trigger is found, the tag for thatcycle is used to determine the indexes pre and post that form the blockof samples to be logged. These beginning and ending tags are rememberedor stored. These are new tags and typically will not align with any ofthe half cycle tags.

So that PQ (Power Quality) event cycles can be linked to theirassociated captures, PQ evaluation of these cycles is postponed untilthey have passed beyond the capture window. In the example case, this is7 half cycles before the trigger and 36 before the just-completed halfcycle. If a PQ event is found, it is logged at this time. Using thebeginning and ending tags of the capture, if any, the PQ event is linkedto its capture waveform before the PQ record goes to flash.

The number of half cycles' lag for PQ and trigger evaluation will changeaccording to the user's pre-trigger and sample rate selections. Thesecounts are determined once at startup and remain constant thereafter. Byusing the numbers for the worst case (65 Hz), correct operation at anyfrequency can be guaranteed.

The worst-case lags occur at 45 Hz. In the example, capture of thewaveform occurs 4.5 cycles later than it might, or 100 msec. Logging ofPQ records occurs 18 cycles after they occur, or 400 msec. For the moretypical 60 Hz case, these values are 25 and 300 msec, respectively. Notethat it will take about 240 msec to save the waveform capture to memory,e.g., flash memory.

Performing a capture once the trigger has been recognized involves thefollwoing steps:

-   -   1. calculate the beginning and ending indexes for the capture        (An index is an offset into the buffer for any particular memory        word. The buffers are circular, so the start and end memory        words might be anywhere in the buffer. Determining a start and        end indexes identifies which part of the buffer to copy and        where to begin and end.)    -   2. copy that portion of the time-locked sample buffer to the aux        buffer    -   3. assign a capture number    -   4. construct the record and save it in flash, and    -   5. wait for flash operation to be complete.        If a second trigger is identified before flashing the first        capture completes, the second capture will exist in the capture        buffer but the remaining part of the buffer is too small to hold        another capture so the buffer will stall. As soon as the first        capture is flashed, the second can begin flashing and the stall        will be canceled. Cycles occurring during a stall cannot become        part of a capture. The RMS buffer never stalls, however, so all        cycles will continue to be checked for PQ events. After a stall        is canceled, no additional captures can occur until the capture        buffer refills.

A full capture includes 2048 samples for 6 channels (24576 bytes), e.g.,three current and three voltage, plus associated record overhead andtrigger information. Each capture will be stored as a set of 26 waveformlog records. The first record holds summary information for the captureas a whole plus the start of the sample data. The remaining 25 recordshold all remaining samples for all channels. This yields a record sizeof 976 bytes. Keeping the records close to the size of the log retrievalbuffer prevents buffer size difficulties during retrieval. The set oflog records will contain:

-   -   Timestamp (in the record header)    -   RMS values for all channels in the trigger cycle    -   Capture number    -   Tag for the trigger [half] cycle    -   ADC calibration for each channel    -   Sample rate    -   Trigger type (RMS, adaptive RMS, wave shape, manual, etc.)    -   Flag(s) to indicate contiguity of one capture with another    -   2048 words of sample data

PQ (Power Quality) log records will contain:

-   -   Timestamp (in the record header).    -   Event identification, i.e. present state & change flags for each        channel    -   Capture number and tag of the [half] cycle causing the event.        Capture number will be zero if the event cycle isn't in a        capture.    -   Additional flags to indicate whether or not the cycle is in a        capture, and if the cycle is only partially in the capture.    -   For departure events, RMS values will be zero.    -   For return to normal events, worst-excursion RMS values for the        channels that returned. Other channels will be zero

It is to be appreciated that events generate a PQ log record,independent of whether or not they are captured. Multiple events in asingle cycle only generate one PQ log record. Triggers and PQ events arelocated by tag numbers. At high sample rates, two contiguous capturescan be logged but subsequent captures will not be contiguous. A secondtrigger within a capture will cause an additional capture to be queued.The additional capture may or may not have the prescribed pre-triggerbut will be contiguous with the first. The same holds true if the secondtrigger occurs up to and including its normal trigger position. If itoccurs after that, a second capture will occur but it won't becontiguous.

Performance

-   -   Multiple Captures

The relative timing between trigger events leads to different captureresults. In all cases, a PQ log record is generated for each cycle thatcontains a trigger event.

TABLE 1 Summary of nominal cycles in capture buffer vs. sample rates:User 60 Hz selected cycles in time to fill nominal sample capturecapture time to flash rate buffer buffer capture 1024 2 0.033 S 0.240 S512 4 0.067 S 0.240 S 256 8 0.133 S 0.240 S 128 16 0.267 S 0.240 S 64 320.533 S 0.240 S 32 64 1.067 S 0.240 S

Refer to Table 1.

If the sample rate is 128 samples per 60 Hertz cycle or slower, writinga capture to the memory, e.g., flash, can be completed in less time thanit takes to refill the capture buffer. This means that, if eventswarrant, contiguous captures can be saved to flash until the meter runsout of erased flash. At sample rates above 128 (256, 512, and 1024) astall will develop if a trigger event is detected while both the captureand aux buffers are in use. Regardless of sample rate, during a flashsector erase, capture will stall if both the capture buffer and theauxiliary buffer fill before the erase completes.

In summary, if the average period of trigger events is less than theflash write time, capturing must stall occasionally and only PQ logrecords will mark events while a save to flash completes. If the averageperiod of the trigger events is more than the flash write time, capturewill stall only if a new event is detected before 2 previous captureshave been written to flash.

In another aspect, the system further includes an envelope type waveformtrigger, wherein the envelope type waveform trigger generates a triggerupon detection of samplings of the at least one scaled, split signalexceeding at least one threshold voltage. The envelope type waveformtrigger is implemented by firmware in processing module 120.

In a further aspect, the envelope type waveform trigger is determinedby,

Vt1−Vth1<Vt2<Vt1+Vth2

where Vt1 is a voltage sampled at time T1 and Vt2 is a voltage sampledat time T2 which is one cycle after time T1 and Vth1 is a first andlower voltage difference and Vth2 is a second and upper voltagedifference so that a bracket is formed surrounding Vt1 that Vt2 isexpected to fall within. Thus, if the signal does not exceed the upperthreshold voltage (=Vt1+Vth2) or fall below the lower threshold voltage(+Vt1−Vth1) there will be no trigger on the envelope type waveshape. Itis envisioned by the present disclosure that there may be additionaltechniques to determine waveform transients and as such they areconsidered as part of this disclosure. Such techniques includecalculating a waveshape quality value by conducting a Fourier transformon the digital samples and then determining the extent of harmonics onthe waveform. If the harmonic magnitudes or the total harmonicdistortion exceed a desired threshold, then it is determined that thewaveshape is not within acceptable standards and, thus a trigger occurs.

Another feature of the IED of the present disclosure is a rate of changefeature. This feature tests the current RMS values of the scaled andconditioned current inputs. Again, this feature is implemented byfirmware within the processing module 120 of the IED and by way ofnon-limiting illustrative example the processor can trigger on a rate ofchange, which is defined as the ratio of the present RMS value and theprevious RMS value. If the rate of change is above the threshold, thenit triggers alerting the user that the rate of change has been exceeded.

The waveform envelope filter or the RMS triggers of the waveformrecording can be configured to also perform an adaptive trigger in whichthe values of the triggers will adapt to the steady state power systemvoltage. As exemplary technique concerning this type of waveformrecording includes collecting 15 minutes of one second updated voltageRMS values (900 values). Then running either a block average or arolling block average or other type of average on the readings. A blockaverage technique consists of adding the 900 voltage readings anddividing by 900 to provide the 15 minute average reading. A rollingaverage consists of calculating the same block average for the voltage,but rolling the block average over a predetermined interval. Thus, auser selects 3 intervals, then the calculation will be done 3 times inthe 15 minute period by adding 900 of the previous 15 minute samplesevery 5 minutes. It is conceived by this invention that other averagingtechniques may be used. Once the average is calculated, then the IEDwill change the triggers assuming that the nominal voltage has changedto the new average voltage value.

The following is an exemplary technique concerning an adaptive trigger.For this example, a simple RMS trigger will be used, however, it iscontemplated by the present disclosure that adaptive trigger can be usedby any of the triggering techniques. Typical power systems utilizeeither a 120 volt, 69 volt or 220 volt Phase to Neutral nominal. Anominal voltage is generally the base voltage that is provided to acustomer. For this example, it is presumed that a base voltage is 120volt nominal. Many factors, however, could cause the base voltage to beslightly higher or lower than a perfect nominal. For instance, when apower system is heavily loaded, it may not be able to supply a full 120volts. Often utility providers can have voltage drift down to 108 voltsat full load. If a customer programs the voltage RMS trigger to trip andrecord an event below 5% of nominal and the nominal is set to 120 volts,the IED will be in a constant trip/recording mode. This is notadvantageous because it could cause the IED to record or trip for steadystate conditions thus using all the memory resources to store theseevents and as such, the IED could record over other useful prior events.Thus, the adaptive algorithm looks at the average voltage to determinewhat the new nominal condition is and then compares the limit to the new“nominal” value based on the average voltage. This adaptation assuresthat the IED is recording events that are actually not stead stateconditions. It is conceived that there are multiple methods that can beused to create an adaptive trigger and that any alternative methods areenvisioned by this invention.

Programmable Settings

Trigger Events bit mapping:

Voltage Voltage Current Voltage manual not used Shape Sag Surge Surgetrigger 0 0 0 C B A C B A C B A C B A 15 14 13 12 11 10 9 8 7 6 5 4 3 21 0

Registers:

1 byte sample rate byte = 5 to 10; rate = (2 {circumflex over ( )} byte)samples per cycle at 60 Hz, i.e. 2 {circumflex over ( )} 5 = 32, 2{circumflex over ( )} 6 = 64, . . . 2 {circumflex over ( )} 10 = 1024 1byte pre-trigger byte = 1 to n − 1; n is the number of (nominal) cyclesper capture 1 word PQ enables see events mapping above; manual triggerbit doesn't apply 1 word trigger always 0 qualifiers 3 words Va, Vb, Vc1 word per channel; word = % full scale (formatted like limits); 0 surgeRMS disables VRMS surge triggering for the channel 3 words Va, Vb, Vc 1word per channel; word = % full scale (formatted like limits); 0 sag RMSdisables VRMS sag triggering for the channel 3 words Ia, Ib, Ic 1 wordper channel; word = % full scale (formatted like limits); 0 surge RMSdisables IRMS surge triggering for the channel 3 words Va, Vb, Vc always0 wave shape threshold

Log Record Formats

-   -   Waveform Record (26 per capture, 976 bytes per record)

No. Byte Byte(s) Contents Notes Offset 12 Record Header All 26 recordsof a capture have the 0 same timestamp 1 Capture Number All 26 recordshave the same capture 12 number. 1 Record Number records in a captureare numbered 13 from 0 to 25 962 Record Payload All 26 record payloadstogether form 12 a composite structure holding all data for the capture.See “waveform capture data organization” below.

-   -   -   Timestamp applied is the time that the trigger was            recognized.        -   Captures are numbered from 1 to 255, then back to 1 again.            Numbering will be consecutive from one capture to the next            as long as there is no reset. A capture number of 0 may            appear in a PQ record, indicating that there is no            associated capture for the PQ cycle, but not in a waveform            record.

    -   Waveform capture data organization (after record headers,        capture numbers, and record numbers have been stripped):

No. Byte(s) No. Word(s) Data 36 18 Information about the capture otherthan actual samples. See “non-sample capture info” below. 388 194Reserved, always 0xFF 2 1 Channel ID for Van or Vab = “AN” or “AB” 40962048 Van or Vab samples 2 1 Channel ID for Ta = “IA” 4096 2048 Iasamples 2 1 Channel ID for Vbn or Vbc = “BN” or “BC” 4096 2048 Vbn orVbc samples 2 1 Channel ID for Ib = “IB” 4096 2048 Ib samples 2 1Channel ID for Vcn or Vca = “CN” or “CA” 4096 2048 Vcn or Vca samples 21 Channel ID for Ic = “IC” 4096 2048 Ic samples

EXAMPLE 26-Record Data Stream (Wye Hookup and Normal Scope Assumed)

record 0 6 record header 0 capture N, record 0 1 non-sample capture info2 FFs 3 Van Channel ID 4 268 Van samples

records 1-3 6 record header 5 capture N, record # 6 481 Van samples

record 4 6 record header  7 capture N, record 4  8 337 Van samples  9 IaChannel ID 10 143 Ia samples

record 5-7 6 record header 11 capture N, record # 12 481 Ia samples

record 8 6 record header 13 capture N, record 8 14 462 Ia samples 15 VbnChannel ID 16 18 Vbn samples

record 9-12 6 record header 17 capture N, record # 18 481 Vbn samples

record 13 6 record header 19 capture N, record 13 20 106 Vbn samples 21Ib Channel ID 22 374 Ib samples

record 14-16 6 record header 23 capture N, record # 24 481 Ib samples

record 17 6 timestamp 25 capture N, record 17 26 231 Ib samples 27 VcnChannel ID 28 249 Vcn samples

record 18-20 6 timestamp 29 capture N, record # 30 481 Vcn samples

record 21 6 timestamp 31 capture N, record 21 32 356 Vcn samples 33 IcChannel ID 34 124 Ic samples

record 22-25 6 timestamp 35 capture N, record # 36 481 Ic samples

-   -   Non-sample capture info (36 bytes total)

No. Byte Byte(s) Contents Notes Offset 1 Sample Rate from ProgrammableSettings 0 1 Flags bit mapped. B0 set indicates this capture 1 iscontiguous with the previous capture; other bits not used, always 0. 1Trigger Type 0 = normal RMS, 1 = adaptive RMS, 2 2 = wave shape, 3-255 =other 1 Reserved always OxFF 3 2 Trigger Source bit mapped per PQenables above 4 2 Trigger Cycle Tag 0-65535 6 2 First Sample Tag 0-655358 2 Last Sample Tag 0-65535 10 2 Trigger Cycle RMS value 0-TBD in TBDunits 12 for Van/Vab Channel 10 Trigger Cycle RMS channels in order Ia,Vb, Ib, Vc, Ic; 14 for Remaining value & units same as above Channels 2Va Sample value 0-TBD. Apply to each Va sample 24 Calibration to obtainactual voltage sampled. See later TBD section for hookupconversions/interpretations. 2 Ia Sample same as above except there areno 26 Calibration hookup issues 4 Vb & Ib Sample same as Va & Ia above28 Calibrations 4 Vc & Ic Sample same as Va & Ia above 32 Calibrations

-   -   PQ Event Record (64 bytes)

No. Byte Byte(s) Contents Notes Offset 12 Record Header 0 2 PresentStates bit mapped per PQ enables above; 0 indicates an 12 untriggeredstate 2 Event Channels bit mapped per PQ enables above; 1 indicates a 14channel changed state and that the change to the present state causedthe event 12 Worst Excursion For events ending a surge or sag episode(e.g. 16 RMS return to normal), RMS of the channel is the worstexcursion (highest surge, lowest sag) for the episode. 0 for otherchannels. Same units as Waveform Records. 1 Capture Number 0 if cyclenot captured, 1-255 if all or part of the 28 cycle was captured 1 FlagsTBD 29 2 Event Cycle Tag Tag of the last sample in the event cycle 30 32not used always 0 32

Although the disclosure herein has been described with reference toparticular illustrative embodiments, it is to be understood that theseembodiments are merely illustrative of the principles and applicationsof the present disclosure. Therefore numerous modifications may be madeto the illustrative embodiments and other arrangements may be devisedwithout departing from the spirit and scope of the present disclosure,which is defined by the appended claims.

Furthermore, although the foregoing text sets forth a detaileddescription of numerous embodiments, it should be understood that thelegal scope of the present disclosure is defined by the words of theclaims set forth at the end of this patent. The detailed description isto be construed as exemplary only and does not describe every possibleembodiment, as describing every possible embodiment would beimpractical, if not impossible. One could implement numerous alternateembodiments, using either current technology or technology developedafter the filing date of this patent, which would still fall within thescope of the claims.

It should also be understood that, unless a term is expressly defined inthis patent using the sentence “As used herein, the term ‘______’ ishereby defined to mean . . . ” or a similar sentence, there is no intentto limit the meaning of that term, either expressly or by implication,beyond its plain or ordinary meaning, and such term should not beinterpreted to be limited in scope based on any statement made in anysection of this patent (other than the language of the claims). To theextent that any term recited in the claims at the end of this patent isreferred to in this patent in a manner consistent with a single meaning,that is done for sake of clarity only so as to not confuse the reader,and it is not intended that such claim term be limited, by implicationor otherwise, to that single meaning. Finally, unless a claim element isdefined by reciting the word “means” and a function without the recitalof any structure, it is not intended that the scope of any claim elementbe interpreted based on the application of 35 U.S.C. §112, sixthparagraph.

What is claimed is:
 1. An intelligent electronic device (IED) havingenhanced power quality and communications capabilities, the IEDcomprising: (a) at least one input channel for receiving AC voltages andcurrents, (b) at least one sensor for sensing the at least one inputvoltage and current channel, (c) at least one analog to digitalconverter for outputting digitized signals, and (d) a processing systemincluding: a volatile memory and a non-volatile memory for storingcaptured waveform samples from at least one of said at least one analogto digital converter, a means to store waveform samples from saidvolatile memory to said non-volatile memory, and a means to trigger tostore said waveform samples based on an adaptive algorithm.
 2. The IEDof claim 1, wherein the IED can transmit data using Ethernet protocol 3.The IED of claim 2, wherein the IED can transmit data using at least oneModbus TCP protocol.
 4. The IED of claim 1, wherein the adaptivealgorithm includes and RMS calculation.
 5. The TED of claim 5 whereinthe adaptive algorithm adapts its voltage based on an average voltagecalculation.
 6. An intelligent electronic device (IED) having enhancedpower quality and communications capabilities, the TED comprising: (a)at least one input channel for receiving AC voltages and currents, (b)at least one sensor for sensing the at least one input voltage andcurrent channel, (c) at least one analog to digital converter foroutputting digitized signals, and (d) a processing system including: avolatile memory and a non-volatile memory for storing captured waveformsamples from at least one of said at least one analog to digitalconverter, a means to store waveform samples from said volatile memoryto said non-volatile memory, and a means to trigger to store saidwaveform samples based on an envelope type waveform trigger algorithm.7. The TED of claim 6, wherein the TED can transmit data using Ethernetprotocol
 8. The IED of claim 7, wherein the TED can transmit data usingat least one Modbus TCP protocol.
 9. The IED of claim 6 wherein theenvelope type waveform trigger algorithm includesVt1−Vth1<Vt2<Vt1+Vth2
 10. The IED of claim 6 wherein the envelope typewaveform trigger algorithm includes a Fourier transform.